C语言每隔1秒读取文件示例

每间隔一段时间读取/proc/sys/kernel/sched_elastic_debug文件里面的值，C语言例子

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

int main()
{
    struct timespec reg, rem;
    FILE *fd;
    int debug;
    size_t st;
    int sec = 1;
    int nsec = 0;
    unsigned long long sleeptime = 0;
    reg.tv_sec = sec;
    reg.tv_nsec = nsec;

    while(1){
        fd = fopen("/proc/sys/kernel/sched_elastic_debug", "r");
        if(!fd){
            printf("open file failed\n");
            exit(1);
        }
        fscanf(fd, "%d", &debug);
        printf("sleeptime:%llu(ns), debug is: %d\n", sleeptime, debug);
        fclose(fd);
        if( -1 == nanosleep(&reg, &rem)){
            printf("error\n");
            exit(1);
        }
        else {
            sleeptime += (sec*1000000000 + nsec);
        }
    }
    return 0;
}